In the construction of bridges and other structures in which pile supports are driven into the earth and are used as supports for the bridge, etc. it is common to form abutment walls about the piles and to backfill the space between the abutment walls and the piles with earth and other materials. For example, U.S. Pat. No. 3,981,038 discloses a backfill barrier wall formed of panels mounted one upon the other and held together with elongated reinforcing straps. As the wall is constructed, the backfill earth is placed in layers beside the wall and about the supporting piles of the bridge abutment.
One of the problems encountered with bridges and other objects supported by piles with backfill earth placed about the piles is that the backfill earth tends to settle over a length of time, and the downward movement of the backfill earth applies a downward load to the piles. The surface friction of the backfill earth with respect to the facing surfaces of the piles tends to transmit a substantial amount of the vertical load of the backfill earth to the pile. This added load tends to deteriorate the piles, sometimes causing enough stress that the piles bend or otherwise become deformed.
One of the prior art techniques for avoiding the application of the downward force from the backfill material against piles is to surround the piles with corrugated steel conduits before the backfill earth is placed adjacent the piles, and filling the tubes with sand, or the like. The relatively fluid sand does not have as much ability to apply the downward forces to the piles, and the circular shape of the steel corrugated conduits tend to shield the pile from the pressure applied by the backfill earth. As a result, the downward settling movement of the backfill earth is applied to the corrugated conduit which tends to move downwardly with the downward movement of the backfill earth, but this downward movement is generally not transmitted from the steel corrugated conduit inwardly through the fill sand to the pile. This generally protects the pile from the downward forces of the backfill earth.
While the aforementioned conduit and sand arrangement has been successful in avoiding deterioration of bridge abutment piles, etc., due to the downward weight applied by settling backfill earth, the use of the corrugated steel conduit and sand in this arrangement is expensive in that the materials are relatively expensive and the labor required to telescopically mount the steel conduits over the piles and then to fill the conduits with sand is expensive.